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Singapore’s Tekong Island has one of the largest mangrove forests in the

country. However, coastal erosion on the northeast coast of Tekong has

threatened these mangroves. To protect them, Singapore undertook a coastal

protection and restoration project. To ensure that the works themselves would

not threaten the existing mangroves, the country's National Parks Board

(NParks) has engaged us through Housing Development Board (HDB) to

develop and implement an EMMP. In doing so, we helped ensure the long-term

sustainability of Tekong’s mangrove forests. Furthermore, we contributed to

furthering knowledge on how to improve the design of Singapore’s coastal

protection structures. This will enable the country to better protect its

mangroves and marine environment in the future.

MANGROVE FORESTS AT RISK

When modern Singapore was first founded, 13% of the country consisted of

mangroves. Important for its biodiversity of plants and animals, mangroves now

account for less than 1% of Singapore’s land area. Singapore’s Tekong Island

contains one of the country’s largest remaining mangrove forests.

SUMMARY

CLIENT

National Parks Board of Singapore (NParks)-Project Initiator

Housing and Development Board of Singapore (HDB)-Managing Agent

CHALLENGE

Risk of loss of rare and endangered mangrove trees due to coastal erosion

Uncertainty about the impact of coastal protection measures on mangroves

SOLUTION

Using an Environmental Monitoring and Management Plan (EMMP) to minimise the impact of coastal protection measures that are put into place to prevent coastal erosion

VALUE

Increased understanding of the effect of coastal protection work on the environment

Ensured protection of Singapore’s largest remaining mangrove forest area

LOCATION / COUNTRY

Tekong Island, Singapore

DHI CASE STORY

PROTECTING SINGAPORE’S MANGROVE FORESTS

Using EMMP to determine the potential impact of construction works

Erosion of the mangrove shoreline at Tekong Island prior to stabilisation of the

shoreline on the island

ENVIRONMENT & ECOSYSTEMS / COAST & MARINE

The island’s northeast coast suffers from coastal erosion,

threatening the mangroves there. To address this,

Singapore’s National Parks Board (NParks) is implementing

coastal protection and restoration works in the area. However,

the coastal protection measures could themselves have a

negative potential impact on the existing mangroves and the

environment. Hence, NParks emphasized that a key

consideration in the design and implementation of works for

the project is that there should be no significant adverse

environmental impact.

To ensure that the above principle was followed through,

NParks insisted on the design and implementation of an

EMMP. Our EMMP ensured that protection measures

undertaken on Tekong Island would not negatively impact:

existing mangrove forests on the island

surrounding waters

offshore aquaculture farm users

Before the construction of the coastal protection measures,

we developed a pre-project baseline of the environmental

conditions. We then used this information during the

construction and demobilisation phases of the project to

monitor the effect on the environment.

PROTECTING MARINE ENVIRONMENTS

As part of the EMMP, we modelled the shoreline to make sure

that the coastal protection measures did not cause a

significant change in currents in the area or increase erosion.

In addition, we conducted surveys of the existing mangrove

forests twice a year. This confirmed that the works conducted

on the shoreline were not negatively affecting the mangroves

further inland on the island.

We also monitored the growth and survival of mangrove

seedlings planted as part of the coastal protection measures.

We conducted 18 monitoring surveys at 20 locations of the

newly planted mangrove seedlings in a 12-month period. This

helped increase understanding of how well mangrove

seedlings tolerate being planted at different degrees of tidal

inundation.

Furthermore, we identified a large amount of natural

regeneration of mangrove seedlings during our monitoring of

newly planted ones. This discovery led to an additional 12

months of surveying on the island to better understand the

phenomenon. The results of the study will help improve the

design of future coastal protection structures, ensuring that

they facilitate natural mangrove colonisation.

Over the course of the project, we also helped the

construction contractor understand the need to minimise the

potential impact of their activities on Singapore’s waters. We

monitored the contractor daily to ensure that the mitigating

measures were effective.

To further protect the fish and oyster farms, we also modelled

sediment plumes created by construction vessels and took

water quality samples offshore to ensure that water quality

offshore was not being negatively affected by work at the site.

By applying a comprehensive EMMP, we helped ensure that

the coastal protection measures were both sustainable and

would not negatively impact Tekong Island’s marine

environment.

Monitoring included monthly measurements of sapling height

and girth, as well as assessment of health condition

DHI CASE STORY ©

DH

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Contact: Eugene Goh - egl@dhigroup.com

For more information visit: www.dhigroup.com

Photo of the shoreline after construction of the shoreline stabilisation

measures showing our monitoring team